Modeling of Entamoeba histolytica ferredoxin

The E. histolytica ferredoxin (EHFXD) is an iron-sulphur protein and is important in the control of E. histolytica because it donates an electron to and activates metronidazole (4) the most effective anti-amoebic drug. The knowledge of the three-dimensional structure of EHFXD can help to assist in rational design of anti-amebic drugs. Homology modeling of EHFXD has been done by using the knowledge of crystal structure of homologous Ferredoxin structures. It has been shown that EHFXD is more likely to contain 2[4Fe-4S] clusters and has a pseudodiad symmetrical fold. The fold is stabilised by hydrophobic patches as well as by intramolecular hydrogen bonds. The importance of two Leu residues in the N- and C-termi in bridging the two clusters has been emphasised. The electrostatic properties of the surface of EHFXD were examined and compared with that of other ferredoxins. It was observed that large regions of negative as well as positive electrostatic potential is a common feature of the [4Fe-4S] containing ferredoxins which might explain their biological role as both electron acceptor and electron donor molecules.